1. Field of the Invention
The invention relates to an image recording apparatus used in copy machines and printers which has a particle control electrode having apertures and controls the flow of charged toner particles passed through the apertures.
2. Description of Related Art
This kind of image recording apparatus includes a toner particle supply source, a particle control electrode having apertures and an electrode roller. The charged toner particles are supplied from the toner particle supply source near the particle control electrode and the flow of the charged toner particles to the apertures is controlled by the particle control electrode. The toner particles controlled so as to pass through the aperture are attracted in the direction of the electrode roller and are attached on a support member which is fed by the electrode roller and an image is formed thereon. As one of this kind of image recording apparatus, there has been proposed, for example, an image recording apparatus disclosed in U.S. Pat. No. 3,689,935.
However, when an image is recorded using the above mentioned image recording apparatus, a problem occurred in that the apertures of the particle control electrode become clogged with the toner particles. U.S. patent application Ser. No. 07/680,728, discloses an image recording apparatus having vibration applying means for vibrating the particle control electrode to prevent the apertures of the particle control electrode from being clogged by the toner particles thereby greatly improving the record stability. Further, the amplitude of the vibration has been greatly increased by making the particle control electrode vibrate with the frequency by which the particle control electrode resonates and thereby the maximum effect is obtained.
However, the toner particles which do not take part in the modulating control by the particle control electrode are also attracted to the particle control electrode. Therefore, a part of the toner particles accumulates in the position where the amplitude of the vibration of the particle control electrode is small, namely the node of the vibration. The resonance frequency of the particle control electrode is changed by the change of weight and form of the particle control electrode caused by this accumulation of the toner particles. On the other hand, the frequency of the vibration applied by the vibration applying means is invariable so that it no longer coincides with the changed resonance frequency of the particle electrode. As a result, the amplitude of the vibration of the particle control electrode becomes small as a whole and the area to which the toner particles are attached extends further. Further, the above adherence of toner particles and the decrease in the amplitude of the vibration of the particle control electrode are repeated until the toner particles are accumulated along the entire surface of the particle control electrode and apertures of the particle control electrode become clogged with the toner particles.